KCNH2 and cardiovascular disorder: Substitution of eq 1 into the Hill equation yields a maximum safe hERG blocker occupancy (γ1) = 3% [21] (by all accounts, a highly stringent safety margin in the absence of underlying cardiovascular disease):γ1=[blocker]free(cell)[blocker]free(cell)+Kd=[blocker]free(cell)[blocker]free(cell)+30⋅[blocker]free(cell)=[blocker]free(cell)31⋅[blocker]free(cell)≅3%(2)